This invention relates generally to a mass spectrometer utilizing an improved sorption pump for maintaining the vessel containing the mass spectrometer at a high vacuum. More specifically, the invention relates to a portable analytical module that includes a mass spectrometer and an improved sorption pump that is removably connected to a service module.
For the most part, sorption pumps cannot maintain the high vacuum pressure required in many analytical process applications and exhibit erratic pumping characteristics both in terms of short term and long term usage. The pumping speed generally falls off rather rapidly as the sorptive materials absorb active gas. Similarly, the ability of the pump to adapt to rapid changes in sample composition is extremely poor. Furthermore, sorption pumps in present use cannot be regenerated in situ and thus, must be changed on a regular basis. Safe handling of the sometimes hazardous sorptive materials during changeover can also pose problems.
In United Kingdom application 2,249,662 there is described a portable mass spectrometer system that includes a gas chromatograph and a mass analyzer housed within a vacuum chamber. A high vacuum ion pump is also housed within the portable system. The pump consumes a good deal of the total electrical energy available and places a heavy load on the system's batteries and restricts the amount of time that is available for sampling in the field.